1. Field of the Invention
The invention relates to automatically controllable projecting contour grinding machines. Such a machine may have a grinding disc support which is displaceable along two mutually perpendicularly disposed axes, with manual actuator elements for displacing this support, and with an optical projection device for throwing an image of the grinding disc and the workpiece to be machined on to a projection surface.
2. Description of the Prior Art
In known projecting contour grinding machines, an image of the grinding disc and an image of the workpiece are produced in an enlarged form on a projection desk, so that the engagement location of the grinding disc can be observed accurately. On the projected image, a transparent carrier has drawn thereon the desired contour line on an appropriately enlarged scale, that is to say the desired contour of the workpiece. By means of a manual control, for example two hand wheels, the grinding disc is displaced, for example on a compound slide rest, in such a manner that the image of the grinding disc on the projection screen follows exactly the desired contour line. Thereby the desired contour is ground into the workpiece at a correspondingly reduced scale. The accuracies obtainable with such known projecting contour grinding machines lie in the order of magnitude of one thousandth of a millimeter, that is to say highly precise devices are involved.
In order to render automatic the displacement of the grinding disc during the machining process, it is already known to scan the desired contour line or a corresponding control line by means of a photocell and to use the movement thereof for controlling the grinding disc support. This control has the disadvantage that it is not well suitable for programmed operation of a projecting contour grinding machine.